An inflatable vehicle occupant protection device, such as an air bag, is inflated upon the occurrence of a vehicle crash. The air bag is part of an apparatus which further includes a crash sensor and an inflator. The crash sensor senses vehicle conditions that indicate the occurrence of a crash. When the crash sensor senses a crash-indicating condition of at least a predetermined threshold level, the inflator is actuated and emits inflation fluid which inflates the air bag into the vehicle occupant compartment. The air bag can then engage a vehicle occupant to help protect the occupant from a forceful impact with parts of the vehicle as a result of the crash.
The inflator includes a container structure defining an inflation fluid pressure chamber with an outlet opening. A rupturable closure disk is fixed and sealed to the container structure to close the outlet opening. The inflator further includes an electrically actuatable initiator which, when actuated, causes the burst disk to rupture so that inflation fluid in the pressure chamber can flow from the inflator to the air bag.